Microwave for one minute (at 550 W).
The edge of the combined miso sauce will have thickened a bit.
Mix the miso sauce well, and microwave for a minute each twice, and 30 seconds each 4 times, mixing each time. When it has thickened about this much it's done.
Since first submitting this recipe I've bought a new microwave, which is 700 W. With this one I microwave for 1 minute each twice, and 30 seconds each 2 to 3 times.
Please cook (microwave) the miso sauce until it's your desired consistency for whatever dish you're using it in. It gets a bit stiffer when cooled, so you can stop cooking it when it's still a bit loose.
I used it on kiritanpo (rice dumpling on a stick).
I added ground sesame seeds and used it on tofu dengaku.
It's also perfect in Myacchu-san's "Easy and Yummy Sweet Onion and Cheese Dengaku" Recipe ID: 573990. It matches perfectly with the onion and cheese.
It can also be used with Recipe ID: 477120 "Pressure Cooked Furofuki Daikon Radish".
Story Behind this Recipe
I don't use red miso much, so I make dengaku miso sauce with white miso (dengaku miso is often made with red miso). The color is gentle, and I love this sauce.
Since it's microwaved several times, the container will get pretty hot, so be careful not to burn yourself.